This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The focus of our structural studies on the 70S ribosome is to obtain high resolution structures of different functional complexes corresponding to different states of the ribosome during translation. Ribosome complexes containing various combinations of mRNA, tRNAs, translational factors and other ligands are being constructed and crystallized for structural analysis. Our ultimate goal is to assemble the resulting structures into a high-resolution 'movie'that will provide a description of translation as it occurs on the ribosome.